fix(pinterest): improve readability and fix unthemed elements

[K1aymore]

🔧 What does this fix? 🔧

I copied the changes from #1405 into here just in case, I wasn't aware of it when I started working.

• Fixes Wrong colors in the Pinterest. Latte, Pink. #1378
• Fixes 4/5 issues in Wrong colors in the Pinterest. Dark Macchiato, Teal. #1301
  • The text on the "Save" button is more readable in different accent colors
  • When hovering over the "Save" button, it dims rather than becoming red
  • When a post is saved, the text in the pop-up message is readable
  • When a post is unsaved, the text in the pop-up message is readable
• The icons when hovering over a pin (among others) now have a dark background in dark themes
• The dropdown of which board to save to is now more readable in dark themes
• The "Created" and "Saved" buttons on the main profile page are themed
• A strange box behind section previews is removed
• The "Invite Collaborators" buttons no longer have a white border around them
• Pin editing mode is themed nicer
• Hover tooltips are no longer inverted (possibly my preference)
• Search dropdown is now the correct color
• Pin view:
  • Fixed the shadow around the pin
  • Increased shadow strength
  • Rounded corners
  • "View larger" and "Image search" buttons properly themed
  • Field for comment entry is no longer transparent

I could not reproduce #1415 but it seems like that is fixed?

What still needs to be fixed:

• Creating new pins menu
• Profile editing menus
• Pin outlines when selected in organization mode and using a dark theme are hard to see

🗒 Checklist 🗒

• I have read and followed Catppuccin's contributing guidelines.
• I have updated the version appropriately in the ==UserStyle== header of the catppuccin.user.css file.

[K1aymore]

Some before and afters:

Before (random unsaved pin):

After:

Before (main profile page):

After:

Before (editing a pin):

After:

Before (the issue from #1378):

After:

Before (issue from #1301):

After:

Before (pin view):

After:

[isabelroses]

thanks for the PR and fixing all those issues :)
Just some small issues with our guidelines.

[isabelroses]

Thanks for the fix :)